A statement from the Dublin Diocesan Liturgical Resource Centre said given the increase in the number of people affected by influenza in recent weeks, “it is opportune to remind ourselves of sensible practices”.

“It is good to remember that those with flu symptoms are dispensed from their Sunday obligation to attend Mass.”

It said those who were confined to home while ill could pray along with the Mass broadcast by Parish Radio.

It did not warn against parishioners offering each other a sign of peace.

“In times of previous flu alerts the Health Service Executive stated: ‘Shaking hands while exchanging the sign of peace involves a low risk of spreading the virus.’

“If some parishioners still feel uncomfortable about shaking hands at the sign of peace, help them to understand that they are very welcome to wish others the Peace of Christ without hand contact (with a smile or a bow),” read the statement.

The HSE has said the current prevalence of both A and B flu viruses is “unusual”, and that this had only happened two or three times in the last 20 years.

Dr Kevin Kelleher, the HSE’s assistant national director for health protection, said “normally our seasons are predominated by the A virus, and the B virus comes along at the tail of the flu season, so this is unusual”.

A H3N2 strain of influenza A, also referred to as “Australian flu” or “Aussie flu” has spread across Britain and Ireland in recent weeks.

At least 170,000 cases were confirmed in Australia by the end of its winter in 2017, more than twice as many as in 2016. Health officials say they logged 72 flu-related deaths.

A statement issued last week from the office of Bishop Noel Treanor said: “Having received medical advice concerning the increasing risk and impact of Australian flu, the Diocese of Down and Connor has decided to reactivate . . . precautionary measures originally established by the diocese in response to the swine flu epidemic in 2009.”